This invention is related to electrical receptacles for use with electrical plugs. In particular, it is an improved electrical receptacle that can be switched at the receptacle.
Electrical receptacles for currents of fifteen amperes or more typically have contacts for three, four or five wires. Such receptacles may injure an operator and may damage the receptacle if they are connected or disconnected to the electric power system under load. For these reasons, it is conventional to provide some form of switch with the receptacle, often interlocked with the receptacle, to insure that the plug is not removed from or inserted into the receptacle under load. The switch is often a safety switch or relay that is installed in a switchbox that serves as a mount for the receptacle. In the alternative, the receptacle may be combined with a circuit breaker. Either of these alternatives increases the cost of installing a receptacle over the cost of the receptacle itself.
It would be useful to have a self-contained receptacle that could be switched to cut off electricity to a plug before the plug is removed from or inserted into the receptacle. Such a receptacle could be operated as a stand-alone device or it could be combined with an interlock as an additional assurance that the plug is not inserted into or removed from the receptacle under load. It would also be useful to have a switching electrical receptacle that would meet requirements for rating for explosion-proof service. Such a switching receptacle could be smaller than a combination safety switch and receptacle, and would therefore be cheaper to manufacture and easier to install. It could also more easily be made explosion-proof because its contacts open and close in a relatively small volume within the receptacle.